JP4803271B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine including an oxidation catalyst provided in an exhaust passage, and a fuel addition valve provided upstream of the oxidation catalyst in the exhaust passage to supply fuel to the oxidation catalyst.

  Conventionally, as a control device of this type of internal combustion engine, for example, there is one described in Patent Document 1. An oxidation catalyst is provided in an exhaust passage of a conventional general internal combustion engine, including the one described in Patent Document 1, and a fuel addition valve for supplying fuel to the oxidation catalyst is provided upstream thereof. ing. In addition, a filter for collecting particulate matter contained in the exhaust gas is provided downstream of the oxidation catalyst in the exhaust passage. Then, by adding fuel to the exhaust gas flowing into the oxidation catalyst by the fuel addition valve, an oxidation reaction is caused through the oxidation catalyst, and the temperature of the exhaust gas flowing into the filter is raised so that the particulate matter is burned and removed. I have to.

JP 2005-256722 A

  By the way, in such an internal combustion engine, if an abnormality occurs in the oxidation catalyst, even if fuel is supplied to the oxidation catalyst, the oxidation reaction through the oxidation catalyst does not proceed favorably. For this reason, the temperature of the exhaust gas flowing into the filter cannot be suitably raised, and there arises a problem that the particulate matter collected by the filter cannot be burned and removed.

  Therefore, a command signal for supplying fuel to the fuel addition valve is output, and when the temperature rise of the oxidation catalyst resulting from this is below a predetermined value, this diagnoses that an abnormality has occurred in the oxidation catalyst. It is possible to do. However, in such a diagnosis mode, even when the fuel addition valve has an abnormality, the temperature rise of the oxidation catalyst may be a predetermined value or less, and the oxidation catalyst is normal although the oxidation catalyst is normal. If the catalyst is abnormal, it will be misdiagnosed.

  On the other hand, if an abnormality occurs in the fuel addition valve, fuel cannot be supplied to the oxidation catalyst, and the oxidation reaction through the oxidation catalyst does not proceed appropriately. For this reason, the temperature of the exhaust gas flowing into the filter cannot be suitably increased, and there arises a problem that the particulate matter collected by the filter cannot be removed by combustion.

  Therefore, a command signal for supplying fuel to the fuel addition valve is output, and if the temperature increase of the oxidation catalyst accompanying this is below a predetermined value, this indicates that an abnormality has occurred in the fuel addition valve. Diagnosis is also possible. However, in such a diagnosis mode, even if an abnormality occurs in the oxidation catalyst, the temperature increase of the oxidation catalyst may be a predetermined value or less, and the fuel addition valve is normal, but the fuel addition valve is normal. If the addition valve is abnormal, it will be misdiagnosed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device for an internal combustion engine that can suppress erroneous diagnosis of the presence or absence of an abnormality in an oxidation catalyst and a fuel addition valve.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
(1) The invention according to claim 1 is an oxidation catalyst provided in an exhaust passage, an air-fuel ratio detection means provided downstream of the oxidation catalyst in the exhaust passage to detect an air-fuel ratio of exhaust, and the exhaust A fuel addition valve provided upstream of the oxidation catalyst and the air-fuel ratio detection means in the passage for supplying fuel to the oxidation catalyst, and by injecting fuel into the cylinder at a time not contributing to engine combustion A fuel injection valve for supplying unburned fuel to the oxidation catalyst, a temperature rise detection means for detecting a temperature rise of the oxidation catalyst accompanying fuel supply by the fuel addition valve or the fuel injection valve, and the oxidation catalyst And a diagnostic means for diagnosing the presence or absence of abnormality of the fuel addition valve, and the diagnostic means outputs a command to supply fuel to the fuel addition valve at the time of the diagnosis, and the oxidation accompanying therewith When the temperature rise of the medium does not correspond to the supply of the fuel, and a command to supply the fuel to the fuel injection valve is output, and the temperature rise of the oxidation catalyst accompanying this increases the temperature of the fuel. When the fuel supply valve is compatible with the supply, a diagnosis is made that the oxidation catalyst is normal and the fuel addition valve is abnormal, while a command to supply fuel to the fuel addition valve is issued during the diagnosis. And when the temperature rise of the oxidation catalyst corresponding to the output does not correspond to the supply of the fuel, and the change in the air-fuel ratio of the exhaust gas corresponding to the increase corresponds to the supply of the fuel. Is for diagnosing that the oxidation catalyst is abnormal and that the fuel addition valve is normal, and for executing the diagnosis for each of the plurality of fuel addition valves provided. When performing diagnostics with, in the control apparatus for an internal combustion engine to prohibit the supply of fuel by the fuel addition valve other than said predetermined fuel addition valve, the internal combustion engine comprises includes a plurality of cylinder banks, the exhaust passage Is provided separately for each cylinder row, and is configured in such a manner that they are gathered together on the downstream side thereof, and the oxidation catalyst and the fuel addition valve are provided separately for each cylinder row. Thus, the gist of the air-fuel ratio detection means is that it is provided on the downstream side of the gathering portion where the exhaust passages gather.

When a command to supply fuel is output to the fuel addition valve and the temperature rise of the oxidation catalyst is not corresponding to the fuel supply, at least one of the fuel addition valve and the oxidation catalyst is abnormal. It can be said that there is. In addition, when a command for supplying fuel is output to the fuel injection valve and the temperature rise of the oxidation catalyst corresponding to the command corresponds to the supply of the fuel, it can be said that at least the oxidation catalyst is normal. . Therefore, as described above, if the existence of abnormality in the oxidation catalyst and the fuel addition valve is diagnosed, if the oxidation catalyst is normal and the fuel addition valve is abnormal, this is accurately diagnosed. Will be able to .
Further, when a command for supplying fuel is output to the fuel addition valve, and the degree of change in the air-fuel ratio of the exhaust corresponding thereto corresponds to the supply of the fuel, at least the fuel addition valve is normal. It can be said. In addition, when the temperature increase of the oxidation catalyst in accordance with the command does not correspond to the supply of the fuel, it can be said that at least one of the fuel addition valve and the oxidation catalyst is abnormal. Therefore, as described above, if the presence or absence of abnormality of the oxidation catalyst and the fuel addition valve is diagnosed, if the oxidation catalyst is abnormal and the fuel addition valve is normal, this is accurately diagnosed. Will be able to.
Therefore, according to the above configuration, it is possible to suppress erroneous diagnosis of the presence or absence of abnormality in the oxidation catalyst and the fuel addition valve.
Further, for example, as in a V-type engine, a plurality of cylinder rows are provided, and exhaust passages are provided for each cylinder row, and are provided in such a manner that they are gathered together on the downstream side thereof. There is an internal combustion engine in which an addition valve is provided for each cylinder row, and an air-fuel ratio detection means is provided downstream of a collecting portion where exhaust passages gather. In such an internal combustion engine, when a command for supplying fuel to the fuel addition valves in each cylinder row at the same time is output when diagnosing whether there is an abnormality in the oxidation catalyst and the fuel addition valve, the oxidation is performed for the following reason. Misdiagnosis of the presence or absence of abnormality of the catalyst and the fuel addition valve cannot be suppressed. That is, for example, when a normal fuel addition valve and an abnormal fuel addition valve are mixed among the fuel addition valves in each cylinder row, if a command to supply fuel to the fuel addition valve at the same time is output, When the fuel is supplied by a simple fuel addition valve, the degree of change in the air-fuel ratio of the exhaust may correspond to the supply of the fuel. Therefore, if the change in the air-fuel ratio of the exhaust gas accompanying the output of the command to supply fuel to the fuel addition valve corresponds to the supply of the fuel, grasp that there is an abnormal fuel addition valve Can not do it. In addition, when the degree of change in the air-fuel ratio of the exhaust does not correspond to the fuel supply, it is possible to grasp that there is an abnormal fuel addition valve, but until the abnormal fuel addition valve is identified. I can't.
In this regard, according to the above configuration, the diagnosis is executed for each cylinder row, and when the diagnosis of the fuel addition valve of a predetermined cylinder row is executed, the supply of fuel by the fuel addition valves of the other cylinder rows is performed. Is prohibited. Here, when a command for supplying fuel is output to the fuel addition valve of a predetermined cylinder row, and the degree of change in the air-fuel ratio of the exhaust corresponding thereto corresponds to the supply of the fuel, at least predetermined It can be said that the fuel addition valve in this cylinder row is normal. Therefore, when an abnormal fuel addition valve exists, it can be specified.

( 2 ) The invention according to claim 2 is the control apparatus for an internal combustion engine according to claim 1 , wherein the diagnosis means outputs a command to supply fuel to the fuel addition valve, and the accompanying When the degree of change in the air-fuel ratio of the exhaust gas does not correspond to the supply of the fuel, a command for supplying fuel to the fuel injection valve is output, and the temperature increase of the oxidation catalyst accompanying this is If it does not correspond to the supply of fuel, the gist is to diagnose that both the oxidation catalyst and the fuel addition valve are abnormal.

  When a command for supplying fuel is output to the fuel addition valve and the change in the air-fuel ratio of the exhaust gas accompanying this is not one corresponding to the fuel supply, it can be said that at least the fuel addition valve is abnormal. In addition, when a command for supplying fuel is output to the fuel injection valve and the temperature rise of the oxidation catalyst associated therewith does not correspond to the supply of the fuel, it can be said that at least the oxidation catalyst is abnormal. Therefore, as described above, if both the oxidation catalyst and the fuel addition valve are diagnosed as abnormal, both the oxidation catalyst and the fuel addition valve can be diagnosed accurately. become able to. Accordingly, it is possible to suppress erroneous diagnosis of the presence or absence of abnormality in the oxidation catalyst and the fuel addition valve.

( 3 ) According to the invention of claim 2, according to the invention of claim 3 , the diagnostic means outputs a command to supply fuel to the fuel addition valve at the time of the diagnosis. When the change in the air-fuel ratio of the exhaust gas does not correspond to the supply of the fuel, the output of the command to the fuel addition valve is stopped, while the command to supply the fuel to the fuel injection valve is issued. It can be embodied with a mode in which the output is diagnosed based on the temperature rise of the oxidation catalyst resulting from this, and whether or not the oxidation catalyst and the fuel addition valve are abnormal.

( 4 ) The invention according to claim 4 is the control apparatus for an internal combustion engine according to claim 3 , wherein the diagnosis means determines the degree of change in the air-fuel ratio of the exhaust gas according to the output of the command to the fuel addition valve. In the case of corresponding to the supply of the fuel, the gist is to prohibit the output of the command to the fuel injection valve in order to diagnose the presence or absence of abnormality of the oxidation catalyst and the fuel addition valve.

  When a command for supplying fuel is output to the fuel addition valve and the change in the air-fuel ratio of the exhaust gas corresponding to this command corresponds to the fuel supply, it can be said that at least the fuel addition valve is normal. . In addition, when the temperature increase of the oxidation catalyst in accordance with the above instruction corresponds to the supply of the fuel, it can be said that the oxidation catalyst is normal, and when the increase in the oxidation catalyst does not correspond to the supply of the fuel, It can be said that the oxidation catalyst is abnormal. That is, when a command to supply fuel is output to the fuel addition valve and the change in the air-fuel ratio of the exhaust gas corresponding to this command corresponds to the fuel supply, both the oxidation catalyst and the fuel addition valve Therefore, it is unnecessary to output a command for supplying fuel to the fuel injection valve thereafter.

  In this regard, according to the above configuration, when a command for supplying fuel is output to the fuel addition valve, and the change in the air-fuel ratio of the exhaust gas corresponding to this command corresponds to the fuel supply, the fuel injection Since the output of the command for supplying fuel to the valve is prohibited, it is possible to suppress the deterioration of the fuel consumption due to the supply of unburned fuel by the fuel injection valve.

( 5 ) According to the invention described in any one of claims 1 to 4 , according to the invention described in claim 5 , the particles contained in the exhaust gas in the exhaust passage downstream of the collecting portion. It can be embodied in such a manner that a filter for collecting the particulate matter is provided.

( 6 ) The gist of the invention according to claim 6 is that, in the control device for an internal combustion engine according to claim 5 , the diagnosis means executes the diagnosis only immediately after the start of the internal combustion engine.

  When the diagnosis of the fuel addition valve of a predetermined cylinder row is executed, the fuel supply by the fuel addition valve of the other cylinder row is prohibited. The oxidation reaction does not occur through the catalyst, and accordingly, the temperature of the exhaust gas flowing into the filter is lowered. Therefore, if an abnormal diagnosis is performed unnecessarily during operation of the internal combustion engine, the temperature of the exhaust gas flowing into the filter cannot be increased suitably, and PM trapped in the filter is preferably burned and removed. The problem of not being able to occur.

  In this respect, according to the above-described configuration, the diagnosis of the abnormality of the oxidation catalyst and the fuel addition valve is performed at a time when the temperature of the exhaust gas flowing into the filter is low, and the particulate matter collected by the filter is burned and removed. Since it is executed only immediately after the start of the internal combustion engine, the particulate matter collected in the filter due to the diagnosis of the presence or absence of abnormality of the oxidation catalyst and the fuel addition valve is removed. It becomes possible to suppress the fact that it can not be suitably removed by combustion.

(7) The invention according to claim 7, in the control apparatus for an internal combustion engine according to claim 5, comprising an exhaust temperature detection means for detecting the temperature of exhaust gas flowing into the filter, said means for diagnosing said exhaust The gist is that the diagnosis is executed only when the temperature of the exhaust gas detected by the temperature detecting means is equal to or higher than a predetermined temperature.

  In the configuration in which the fuel supply by the fuel addition valves of the other cylinder rows is prohibited when the diagnosis of the fuel addition valve of the predetermined cylinder row is executed, the oxidation of the cylinder row in which the fuel supply is prohibited Since the oxidation reaction is difficult to proceed with the catalyst, the temperature of the exhaust gas flowing into the filter is lowered accordingly. As a result, there is a problem that the temperature of the exhaust gas flowing into the filter cannot be suitably raised, and the particulate matter collected by the filter cannot be suitably removed by combustion.

  In this respect, according to the above configuration, since the diagnosis of whether there is an abnormality in the oxidation catalyst and the fuel addition valve is performed when the temperature of the exhaust gas flowing into the filter is high to some extent, the oxidation catalyst and the fuel addition valve are It is possible to prevent the particulate matter trapped in the filter from being suitably burned and removed due to the execution of the diagnosis of the presence or absence of the abnormality.

( 8 ) According to the invention described in any one of claims 1 to 7 , according to the invention described in claim 8 , the temperature rise detection means detects the temperature of the exhaust gas flowing out from the oxidation catalyst. And a downstream exhaust temperature sensor that detects the temperature increase of the oxidation catalyst based on the detection result of the downstream exhaust temperature sensor.

1 is a schematic configuration diagram showing a schematic configuration of an embodiment of a control device for an internal combustion engine according to the present invention. The table | surface for demonstrating the principle of the abnormality diagnosis of this embodiment. The flowchart which shows the process sequence of abnormality diagnosis control of this embodiment. The flowchart which shows the process sequence of abnormality diagnosis control of this embodiment. The schematic block diagram which shows the schematic structure about the modification of the control apparatus of the internal combustion engine which concerns on this invention. The schematic block diagram which shows the schematic structure about the other modification of the control apparatus of the internal combustion engine which concerns on this invention. The schematic block diagram which shows the schematic structure about the other modification of the control apparatus of the internal combustion engine which concerns on this invention. The schematic block diagram which shows the schematic structure about the other modification of the control apparatus of the internal combustion engine which concerns on this invention. The schematic block diagram which shows the schematic structure about the other modification of the control apparatus of the internal combustion engine which concerns on this invention.

  1 to 4, an internal combustion engine control device according to the present invention is embodied as a control device for a V-type 8-cylinder diesel engine (hereinafter, "internal combustion engine 10"). Will be described.

FIG. 1 shows a schematic configuration of a control device for an internal combustion engine according to the present embodiment.
As shown in the figure, the internal combustion engine 10 includes two cylinder rows each having four cylinders (the upper cylinder row in the figure is the first cylinder row 11 and the lower cylinder row in the figure is the second cylinder row 21). Yes).

  Each cylinder row 11, 21 is provided with a pressure accumulation pipe 13, 23, respectively. Each cylinder is provided with fuel injection valves 14 and 24 that are connected to the pressure accumulating pipes 13 and 23 and inject fuel directly into the combustion chambers 12 and 22. The fuel pumped from the fuel pump (not shown) to the pressure accumulating pipes 13 and 23 is accumulated in the pressure accumulating pipes 13 and 23, and supplied to the combustion chambers 12 and 22 of the cylinders through the fuel injection valves 14 and 24, respectively. Is done. An intake passage is connected to each of the cylinder rows 11 and 21.

  A first exhaust pipe 15 and a second exhaust pipe 25 are connected to each cylinder row 11 and 21 separately. These exhaust pipes 15 and 25 are connected to a common third exhaust pipe 30 on the downstream side thereof. The first exhaust pipe 15, the second exhaust pipe 25, and the third exhaust pipe 30 correspond to the exhaust passage according to the present invention.

  In the middle of the first exhaust pipe 15 and the second exhaust pipe 25, oxidation catalysts 17 and 27 are provided, respectively. Further, in the first exhaust pipe 15 and the second exhaust pipe 25, fuel is added to the exhaust gas flowing into the oxidation catalysts 17 and 27 on the upstream side of the oxidation catalysts 17 and 27, and the fuel is supplied to the oxidation catalysts 17 and 27. Fuel supply valves 16 and 26 to be supplied are respectively provided. The fuel addition valves 16 and 26 are respectively supplied with fuel from a fuel pump (not shown).

  Particulate matter (hereinafter referred to as “PM”) contained in the exhaust is collected downstream of the collecting portion 30A where the first exhaust pipe 15 and the second exhaust pipe 25 gather in the third exhaust pipe 30. A filter 31 is provided.

  In such a configuration, the air supplied to each cylinder through the intake passage and the fuel injected and supplied from the fuel injection valves 14 and 24 are mixed in the combustion chambers 12 and 22, and the mixed gas thus mixed is the combustion chambers 12 and 22. At 22 it is subjected to combustion. The engine output shaft is rotationally driven by the expansion energy resulting from the combustion. Further, the exhaust gas generated by the combustion in the combustion chambers 12 and 22 is discharged to the exhaust pipes 15 and 25, and when passing through the oxidation catalysts 17 and 27, hydrocarbons (HC) and carbon monoxide ( CO) is oxidized and purified. Further, the exhaust gas that has passed through the oxidation catalysts 17 and 27 is discharged to the third exhaust pipe 30, and when it passes through the filter 31, PM contained in the exhaust gas is collected.

  The electronic control unit 40 that controls the internal combustion engine 10 is configured to include a microcomputer. The electronic control device 40 receives detection signals from various sensors for detecting the engine operating state.

  The various sensors include, for example, upstream exhaust temperature sensors 51 and 61 that detect the temperature Tgin of the exhaust gas flowing into the oxidation catalysts 17 and 27, and downstream exhaust temperature sensors that detect the temperature Tgout of the exhaust gas that flows out of the oxidation catalysts 17 and 27. 52 and 62 and an air-fuel ratio sensor 71 for detecting the air-fuel ratio A / F of the exhaust is provided. Here, the upstream side exhaust temperature sensors 51 and 61 are provided upstream of the oxidation catalysts 17 and 27 in the exhaust pipes 15 and 16, respectively. Further, the downstream side exhaust temperature sensors 52 and 62 are provided on the downstream side of the oxidation catalysts 17 and 27 in the exhaust pipes 15 and 16, respectively. The air-fuel ratio sensor 71 is provided on the downstream side of the filter 31 in the third exhaust pipe 30. In addition, an accelerator opening sensor that detects the accelerator opening that is the amount of depression of the accelerator pedal, an engine rotation speed sensor that detects the engine rotation speed that is the rotation speed of the engine output shaft, the combustion chamber 12 through the intake passage, An intake air amount sensor or the like (not shown) for detecting the intake air amount that is the amount of intake air supplied to 22 is provided as necessary.

  The electronic control unit 40 performs various calculations based on detection signals from various sensors, and executes operation control of the fuel injection valves 14 and 24 and operation control of the fuel addition valves 16 and 26 based on the calculation results.

  Further, the electronic control unit 40 estimates the amount of PM deposited on the filter 31 based on the engine operating state. When the accumulated amount of PM becomes a predetermined amount or more, the fuel is added to the exhaust gas flowing into the oxidation catalysts 17 and 27 by operating the fuel addition valves 16 and 26. As a result, an oxidation reaction is caused through the oxidation catalysts 17 and 27, and the temperature of the exhaust gas flowing into the filter 31 is raised to burn and remove PM.

  Further, the electronic control unit 40 performs post injection for injecting fuel into the cylinder from the expansion stroke to the exhaust stroke, that is, at a time not contributing to engine combustion, by operating the fuel injection valves 14 and 24 as necessary. To do. As a result, unburned fuel is supplied to the oxidation catalysts 17 and 27.

  By the way, in such an internal combustion engine 10, when an abnormality occurs in the oxidation catalysts 17 and 27, even if fuel is supplied to the oxidation catalysts 17 and 27, the oxidation reaction through the oxidation catalysts 17 and 27 suitably proceeds. No longer. For this reason, the temperature of the exhaust gas flowing into the filter 31 cannot be suitably raised, and there arises a problem that PM trapped in the filter 31 cannot be burned and removed.

  Therefore, for example, when a command signal for supplying fuel to the fuel addition valves 16 and 26 is output and the accompanying temperature increase ΔTC of the oxidation catalysts 17 and 27 is equal to or less than a predetermined value, the oxidation catalyst is thereby used. It is conceivable to diagnose that an abnormality has occurred in 17 and 27. However, in such a diagnosis mode, even when the fuel addition valves 16 and 26 are abnormal, the temperature increase ΔTC of the oxidation catalysts 17 and 27 may be a predetermined value or less. In spite of normality, it is erroneously diagnosed that an abnormality has occurred in the oxidation catalysts 17, 27.

  On the other hand, if an abnormality occurs in the fuel addition valves 16 and 26, fuel cannot be supplied to the oxidation catalysts 17 and 27, and the oxidation reaction through the oxidation catalysts 17 and 27 does not proceed appropriately. For this reason, the temperature of the exhaust gas flowing into the filter 31 cannot be suitably raised, and there is a problem that the PM collected by the filter 31 cannot be burned and removed.

  Therefore, a command signal for supplying fuel to the fuel addition valves 16 and 26 is output, and when the temperature increase ΔTC of the oxidation catalysts 17 and 27 accompanying this is below a predetermined value, this is the fuel addition valve. It is also conceivable to diagnose that an abnormality has occurred in 16, 26. However, in such a diagnosis mode, even when the oxidation catalysts 17 and 27 are abnormal, the temperature increase ΔTC of the oxidation catalysts 17 and 27 may be a predetermined value or less, and the fuel addition valve is normal. In spite of the fact, the fuel addition valves 16 and 26 are erroneously diagnosed as having an abnormality.

  Therefore, in the present embodiment, a command for supplying fuel to the fuel addition valve 16 (26) is output through the electronic control unit 40, and the temperature increase ΔTC of the oxidation catalyst 17 (27) and the exhaust air exhaust gas accordingly. The presence or absence of abnormality of the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) is diagnosed based on the change rate ΔA / F of the fuel ratio. Further, a command to execute post injection is output to the fuel injection valve 14 (24), and the oxidation catalyst 17 (27) and the fuel addition valve 16 are based on the temperature increase ΔTC of the oxidation catalyst 17 (27) accompanying this. The presence or absence of abnormality (26) is diagnosed. This suppresses misdiagnosis of the presence or absence of abnormality of the oxidation catalyst 17 (27) and the fuel addition valve 16 (26). Here, in the present embodiment, the oxidation catalysts 17 and 27 accompanying the fuel supply by the fuel addition valve 16 (26) or the fuel injection valve 14 (24) based on the detection result of the downstream side exhaust temperature sensor 52 (62). The temperature rise ΔTC is detected. The electronic control unit 40 and the downstream side exhaust temperature sensor 52 (62) correspond to the temperature rise detection means according to the present invention.

  In the internal combustion engine 10 in which a plurality of fuel addition valves 16 and 26 are provided on the upstream side of the air-fuel ratio sensor 71 as in the present embodiment, the oxidation catalysts 17 and 27 and the fuel addition valves 16 and 26 are abnormal. When a command to supply fuel to the fuel addition valves 16 and 26 of the cylinder rows 11 and 21 at the same time is output in the diagnosis of the presence or absence of the oxidation catalyst 17 and 27 and the fuel addition valves 16 and 26 for the following reason. It is not possible to suppress misdiagnosis of 26 abnormalities. That is, for example, when a normal fuel addition valve and an abnormal fuel addition valve are mixed in the fuel addition valves 16 and 26 of the cylinder rows 11 and 21, fuel is simultaneously supplied to the fuel addition valves 16 and 26. When the command to output is output, the fuel is supplied by the normal fuel addition valve, so that the change degree ΔA / F of the air-fuel ratio of the exhaust gas may correspond to the supply of the fuel. Therefore, if the change degree ΔA / F of the air-fuel ratio of the exhaust gas accompanying the output of the command to supply fuel to the fuel addition valves 16 and 26 corresponds to the fuel supply, an abnormal fuel addition valve Can't figure out that exists. In addition, if the change degree ΔA / F of the air-fuel ratio of the exhaust gas does not correspond to the supply of the fuel, it can be understood that there is an abnormal fuel addition valve, but the abnormal fuel addition valve is identified. You can't do it.

  Therefore, in the present embodiment, the diagnosis is executed for each fuel addition valve 16 (26) through the electronic control unit 40. That is, when the diagnosis of the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) in the predetermined cylinder row 11 (21) is executed, the fuel addition valve 16 (26 in the predetermined cylinder row 11 (21) is performed. The fuel supply by the fuel addition valve 26 (16) other than () is prohibited. Thereby, when there is an abnormal fuel addition valve 16 (26), it is specified.

Hereinafter, the principle of abnormality diagnosis of the present embodiment will be described with reference to FIG. FIG. 2 shows the abnormal portion, the change rate ΔA / F of the air-fuel ratio when a command for supplying fuel to the fuel addition valve 16 (26) is output, and the temperature increase ΔTC of the oxidation catalyst 17 (27). And a table showing the relationship between the temperature increase ΔTC of the oxidation catalyst 17 (27) when a command to supply fuel is output to the fuel injection valve 14 (24). That is, when the fuel addition valve 16 (26) or the oxidation catalyst 17 (27) is normal, “◯” is added to the corresponding column, and the fuel addition valve 16 (26) or the oxidation catalyst 17 (27). Is abnormal, “×” is added to the corresponding column. Further, when the change degree ΔA / F of the air-fuel ratio of the exhaust gas or the temperature increase ΔTC of the oxidation catalyst 17 (27) corresponds to the supply of the fuel, “◯” is added to the corresponding column. In the case where the change degree ΔA / F of the air-fuel ratio of the exhaust gas or the temperature increase ΔTC of the oxidation catalyst 17 (27) does not correspond to the supply of the fuel, “X” is added to the corresponding column. .
<Case 1 (Both fuel addition valve 16 (26) and oxidation catalyst 17 (27) are normal)>
A command for supplying fuel is output to the fuel addition valve 16 (26) through the electronic control unit 40, and the temperature increase ΔTC of the oxidation catalyst 17 (27) associated therewith corresponds to the supply of the fuel. In this case, it can be said that both the fuel addition valve 16 (26) and the oxidation catalyst 17 (27) are normal.
<Case 2 (Oxidation catalyst 17 (27) is abnormal and fuel addition valve 16 (26) is normal)>
When a command to supply fuel is output to the fuel addition valve 16 (26) through the electronic control unit 40, and the accompanying temperature increase ΔTC of the oxidation catalyst 17 (27) does not correspond to the fuel supply It can be said that at least one of the fuel addition valve 16 (26) and the oxidation catalyst 17 (27) is abnormal (cases 2, 3, and 4 correspond in the figure). In addition, when the change degree ΔA / F of the air-fuel ratio of the exhaust gas in accordance with the command corresponds to the supply of the fuel, it can be said that at least the fuel addition valve 16 (26) is normal (in the drawing, Cases 1 and 2 apply). For these reasons, a command to supply fuel is output to the fuel addition valve 16 (26), and the accompanying temperature increase ΔTC of the oxidation catalyst 17 (27) does not correspond to the fuel supply. If the air fuel ratio change ΔA / F of the exhaust gas in accordance with the command corresponds to the fuel supply, the oxidation catalyst 17 (27) is abnormal and the fuel addition valve 16 (26 ) Is normal.
<Case 3 (Oxidation catalyst 17 (27) is normal and fuel addition valve 16 (26) is abnormal)>
When a command to supply fuel is output to the fuel addition valve 16 (26) through the electronic control unit 40, and the accompanying temperature increase ΔTC of the oxidation catalyst 17 (27) does not correspond to the fuel supply It can be said that at least one of the fuel addition valve 16 (26) and the oxidation catalyst 17 (27) is abnormal (cases 2, 3, and 4 correspond in the figure). Further, a command to execute post injection is output to the fuel injection valve 14 (24) through the electronic control unit 40, and the temperature increase ΔTC of the oxidation catalyst 17 (27) corresponding to this command corresponds to the supply of the fuel. If it is, it can be said that at least the oxidation catalyst 17 (27) is normal (cases 1 and 3 correspond in the figure). For these reasons, a command to supply fuel is output to the fuel addition valve 16 (26), and the accompanying temperature increase ΔTC of the oxidation catalyst 17 (27) does not correspond to the fuel supply. Yes, and a command to execute post-injection is output to the fuel injection valve 14 (24), and the accompanying temperature increase ΔTC of the oxidation catalyst 17 (27) corresponds to the fuel supply. It can be said that the oxidation catalyst 17 (27) is normal and the fuel addition valve 16 (26) is abnormal.
<Case 4 (Both oxidation catalyst 17 (27) and fuel addition valve 16 (26) are abnormal)>
A command for supplying fuel is output to the fuel addition valve 16 (26) through the electronic control unit 40, and the change degree ΔA / F of the air-fuel ratio of the exhaust gas accompanying this is not corresponding to the fuel supply. It can be said that at least the fuel addition valve 16 (26) is abnormal (cases 3 and 4 are applicable in the figure). Further, a command to execute post injection is output to the fuel injection valve 14 (24) through the electronic control unit 40, and the temperature increase ΔTC of the oxidation catalyst 17 (27) corresponding to this command corresponds to the supply of the fuel. If not, it can be said that at least the oxidation catalyst 17 (27) is abnormal (cases 2 and 4 are applicable in the figure). For these reasons, a command to supply fuel is output to the fuel addition valve 16 (26), and the change degree ΔA / F of the air-fuel ratio of the exhaust accompanying this is not corresponding to the fuel supply. In addition, when a command to execute post-injection is output to the fuel injection valve 14 (24), and the accompanying temperature increase ΔTC of the oxidation catalyst 17 (27) does not correspond to the supply of the fuel, It can be said that both the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) are abnormal.

The principle of the abnormality diagnosis is based on the premise that the fuel injection valves 14 and 24, the downstream exhaust temperature sensors 52 and 62, and the air-fuel ratio sensor 71 are all normal.
Next, the abnormality diagnosis control of this embodiment will be described with reference to FIGS. 3 and 4 are flowcharts showing a processing procedure for abnormality diagnosis control. A series of processing shown in this flowchart is repeatedly executed by the electronic control unit 40 during operation of the internal combustion engine 10.

  As shown in FIG. 3, in this process, it is first determined whether or not an abnormality diagnosis execution condition is satisfied (step S101). The execution conditions here are that the elapsed period from the completion of the start of the internal combustion engine 10 is within a predetermined range, that is, immediately after the start of the internal combustion engine 10, or until the previous control cycle. The abnormality diagnosis of the oxidation catalysts 17 and 27 and the fuel addition valves 16 and 26 in the cylinder rows 11 and 21 is not completed. Here, the reason why the abnormality diagnosis is executed only immediately after the internal combustion engine 10 is started will be described. That is, in this embodiment, when the diagnosis of the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) of a predetermined cylinder row 11 (21) is executed, the fuel of the other cylinder row 21 (11) is used. The supply of fuel by the addition valve 26 (16) is prohibited. Therefore, in the cylinder row 21 (11) where the supply of fuel is prohibited, the oxidation reaction does not occur through the oxidation catalyst 27 (17), and the temperature of the exhaust gas flowing into the filter 31 is lowered accordingly. Therefore, if an abnormal diagnosis is performed unnecessarily during operation of the internal combustion engine 10, the temperature of the exhaust gas flowing into the filter 31 cannot be suitably raised, and the PM collected in the filter 31 is suitably burned. The problem that it cannot be removed arises. Therefore, in the present embodiment, the abnormality diagnosis is only performed immediately after the start of the internal combustion engine 10 when the temperature of the exhaust gas flowing into the filter 31 is low and the necessity of burning and removing the PM collected by the filter 31 is low. By executing the above, it is possible to prevent the PM collected in the filter 31 from being suitably burned and removed due to the execution of the abnormality diagnosis.

In step S101, when the execution condition is not satisfied (step S101: “NO”), the series of processes is temporarily ended.
On the other hand, if the execution condition is satisfied in step S101 (step S101: “YES”), the fuel addition valve 16 (26) of the cylinder row 11 (21) to be subjected to abnormality diagnosis is then applied. Only for that, a command to supply fuel is output (step S102). Next, the temperature increase ΔTC and the change rate ΔA / F of the air-fuel ratio of the oxidation catalyst 17 (27) of the cylinder row 11 (21) to be subjected to abnormality diagnosis are read (step S103). Here, the temperature increase ΔTC of the oxidation catalyst 17 (27) is calculated as a deviation of the value of the exhaust temperature Tgout before and after the command is output to the fuel addition valve 16 (26). Further, the change rate ΔA / F of the air-fuel ratio is calculated as a deviation of the value of the air-fuel ratio A / F before and after the command is output to the fuel addition valve 16 (26). It should be noted that there is a predetermined time delay from when the fuel supply command is output to the fuel addition valve 16 (26) until the exhaust gas temperature Tgout actually changes or the air-fuel ratio A / F changes. Therefore, in the present embodiment, the process of step S103 is executed after a predetermined period has elapsed since the process of step S102 was executed.

  When the temperature increase ΔTC and the air-fuel ratio change degree ΔA / F of the oxidation catalyst 17 (27) are thus read, it is next determined whether or not the air-fuel ratio change degree ΔA / F is equal to or greater than a predetermined value B1 ( Step S104). Here, the predetermined value B1 is a value set in advance through experiments. When the change rate ΔA / F of the air-fuel ratio is not equal to or greater than the predetermined value B1 (step S104: “NO”), the change rate ΔA / F of the exhaust air-fuel ratio corresponding to the command corresponds to the supply of the fuel. If not, the process proceeds to step S109.

  On the other hand, when the air-fuel ratio change degree ΔA / F is equal to or greater than the predetermined value B1 in step S104 (step S104: “YES”), the air-fuel ratio change degree ΔA / F of the exhaust gas accompanying the command is Next, it is determined whether the temperature increase ΔTC of the oxidation catalyst 17 (27) is equal to or greater than a predetermined value C1 (step S105). Here, the predetermined value C1 is a value set in advance through experiments. If the temperature increase ΔTC of the oxidation catalyst 17 (27) is not equal to or greater than the predetermined value C1 (step S105: “NO”), the temperature increase ΔTC of the oxidation catalyst 17 (27) in accordance with the command is equal to that of the fuel. It is diagnosed that the oxidation catalyst 17 (27) is abnormal and the fuel addition valve 16 (26) is normal (step S106).

  On the other hand, in step S105, when the temperature increase ΔTC of the oxidation catalyst 17 (27) is equal to or greater than the predetermined value C1 (step S105: “YES”), the temperature increase of the oxidation catalyst 17 (27) in accordance with the command. Assuming that the combined ΔTC corresponds to the fuel supply, it is diagnosed that both the fuel addition valve 16 (26) and the oxidation catalyst 17 (27) are normal (step S106).

  In step S109, a command for executing post-injection is output only to the fuel injection valve 14 (24) of the cylinder row 11 (21) to be subjected to abnormality diagnosis. Next, the temperature increase ΔTC of the oxidation catalyst 17 (27) of the cylinder row 11 (21) to be subjected to abnormality diagnosis is read (step S110). Here, the temperature increase ΔTC of the oxidation catalyst 17 (27) is calculated as a deviation of the value of the exhaust gas temperature Tgout before and after the command is output to the fuel injection valve 14 (24). Here, the process of step S110 is executed after a predetermined period has elapsed since the process of step S109 was executed, for the same reason as the process of step S103.

  When the temperature increase ΔTC of the oxidation catalyst 17 (27) is thus read, it is next determined whether or not the temperature increase ΔTC of the oxidation catalyst 17 (27) is equal to or greater than a predetermined value C2 (step S111). Here, the predetermined value C2 is a value set in advance through experiments. When the temperature increase ΔTC of the oxidation catalyst 17 (27) is not equal to or greater than the predetermined value C2 (step S111: “NO”), the temperature increase ΔTC of the oxidation catalyst 17 (27) in accordance with the command is determined as that of the fuel. It is diagnosed that both of the fuel addition valve 16 (26) and the oxidation catalyst 17 (27) are abnormal because they do not correspond to the supply (step S112).

  On the other hand, if the temperature increase ΔTC of the oxidation catalyst 17 (27) is equal to or greater than the predetermined value C1 in step S111 (step S111: “YES”), the temperature increase of the oxidation catalyst 17 (27) in accordance with the above command. Assuming that the combined ΔTC corresponds to the fuel supply, it is diagnosed that the oxidation catalyst 17 (27) is normal and the fuel addition valve 16 (26) is abnormal (step S113).

  When the abnormality diagnosis for the target cylinder row 11 (21) is completed in the above steps S106, S107, S112, and S113, the target cylinder row 21 (11) is then switched (step S108), and this series of processes is temporarily ended. To do.

  In the abnormality diagnosis control, when the change rate ΔA / F of the air-fuel ratio of the exhaust gas accompanying the output of the command to the fuel addition valve 16 (26) corresponds to the fuel supply (step S104: “ YES ”), the presence or absence of abnormality in both the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) can be accurately diagnosed. Thereafter, post-injection is performed on the fuel injection valve 14 (24). It is not necessary to output a command to be executed. Therefore, in order to suppress the deterioration of the fuel consumption due to the execution of the post injection by the fuel injection valve 14 (24), the process does not proceed to step S109, that is, the post with respect to the fuel injection valve 14 (24). The output of the command for executing the injection is prohibited.

According to the control apparatus for an internal combustion engine according to the present embodiment described above, the following effects can be obtained.
(1) When an abnormality is diagnosed through the electronic control unit 40, a command for supplying fuel to the fuel addition valve 16 (26) is output, and as a result, the temperature increase ΔTC of the oxidation catalyst 17 (27) is determined. This is a case that does not correspond to the supply, and a command to execute post injection is output to the fuel injection valve 14 (24), and the temperature increase ΔTC of the oxidation catalyst 17 (27) accompanying this is the supply of the fuel. If it corresponds to the above, it is determined that the oxidation catalyst 17 (27) is normal and the fuel addition valve 16 (26) is abnormal (case 3). As a result, when the oxidation catalyst 17 (27) is normal and the fuel addition valve 16 (26) is abnormal, this can be diagnosed accurately. Accordingly, it is possible to suppress erroneous diagnosis of the presence or absence of abnormality of the oxidation catalyst 17 (27) and the fuel addition valve 16 (26).

  (2) When an abnormality is diagnosed through the electronic control unit 40, a command for supplying fuel to the fuel addition valve 16 (26) is output, and as a result, the temperature increase ΔTC of the oxidation catalyst 17 (27) is determined. If it does not correspond to the supply and the change rate ΔA / F of the air-fuel ratio of the exhaust gas according to the command corresponds to the supply of the fuel, the oxidation catalyst 17 (27) is abnormal, and It was decided to diagnose that the fuel addition valve 16 (26) is normal (case 2). Thereby, when the oxidation catalyst 17 (27) is abnormal and the fuel addition valve 16 (26) is normal, this can be diagnosed accurately. Accordingly, it is possible to suppress erroneous diagnosis of the presence or absence of abnormality of the oxidation catalyst 17 (27) and the fuel addition valve 16 (26).

  (3) When an abnormality is diagnosed through the electronic control unit 40, a command for supplying fuel to the fuel addition valve 16 (26) is output, and the change degree ΔA / F of the air-fuel ratio of the exhaust gas accompanying this is supplied. And a command to execute post-injection is output to the fuel injection valve 14 (24), and the temperature increase ΔTC of the oxidation catalyst 17 (27) associated with this is supplied to supply the fuel. If not, it was decided that both the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) were abnormal (case 4). As a result, when both the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) are abnormal, this can be diagnosed accurately. Accordingly, it is possible to suppress erroneous diagnosis of the presence or absence of abnormality of the oxidation catalyst 17 (27) and the fuel addition valve 16 (26).

  (4) When an abnormality is diagnosed through the electronic control unit 40, a command for supplying fuel to the fuel addition valve 16 (26) is output, and the change degree ΔA / F of the air-fuel ratio of the exhaust gas accompanying this is supplied. If the output does not correspond to the above, the output of the command to the fuel addition valve 16 (26) is stopped, while the command to execute the post injection is output to the fuel injection valve 14 (24). Whether or not the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) are abnormal is diagnosed based on the temperature increase ΔTC of the catalyst 17 (27). When the change degree ΔA / F of the air-fuel ratio of the exhaust gas accompanying the output of the command to the fuel addition valve 16 (26) corresponds to the supply of the fuel, the oxidation catalyst 17 (27) and the fuel addition In order to diagnose the presence or absence of abnormality of the valve 16 (26), the output of the command to the fuel injection valve 14 (24) is prohibited. Thereby, the deterioration of the fuel consumption resulting from the fuel supply by the fuel injection valve 14 (24) can be suppressed.

  (5) The diagnosis is executed for each predetermined cylinder row 11 (21) through the electronic control unit 40. When the diagnosis for the predetermined cylinder row 11 (21) is executed, the predetermined cylinder row 11 ( The fuel supply by the fuel addition valve 26 (16) other than the fuel addition valve 16 (26) of 21) is prohibited. Thereby, when there is an abnormal fuel addition valve 16 (26), it can be specified.

  (6) Only immediately after the internal combustion engine 10 is started, the diagnosis of whether or not the oxidation catalyst 17 (27) and the fuel addition valve 16 (26) are abnormal is executed. As a result, it is possible to prevent the PM collected by the filter 31 from being suitably removed by combustion due to the execution of the abnormality diagnosis.

Note that the control device for an internal combustion engine according to the present invention is not limited to the configuration exemplified in the above embodiment, and can be implemented as, for example, the following forms appropriately modified.
In the embodiment described above, the temperature increase ΔTC of the oxidation catalyst 17 (27) is detected based on the detection result of the downstream side exhaust temperature sensor 52 (62). For example, in addition to the detection result of the downstream exhaust temperature sensor 52 (62), the rise of the oxidation catalyst 17 (27) is based on the detection result of the upstream exhaust temperature sensor 51 (61). The temperature degree ΔTC may be detected, or alternatively, a sensor for directly detecting the temperature of the oxidation catalyst 17 (27) may be provided.

  In the above embodiment, the abnormality diagnosis is executed only immediately after the internal combustion engine 10 is started, but the diagnosis time by the diagnosis means according to the present invention is not limited to this. In addition, for example, the diagnosis may be executed only when the temperature Tgout of the exhaust gas flowing out from the oxidation catalyst 17 (27) is equal to or higher than a predetermined temperature. Thus, the abnormality diagnosis is executed when the temperature of the exhaust gas flowing into the filter 31 is high to some extent, so that the PM collected in the filter 31 due to the execution of the abnormality diagnosis can be suitably burned and removed. It becomes possible to suppress the inability to do so. Further, the means for detecting the temperature of the exhaust gas flowing into the filter 31 is not limited to the detection result of the downstream exhaust temperature sensor 52 (62), and any means for detecting the temperature of the exhaust gas flowing into the filter 31 can be used. The configuration of the exhaust gas temperature detecting means can be arbitrarily changed.

  In the above-described embodiment, the V-type internal combustion engine 10 is illustrated, but the internal combustion engine according to the present invention is not limited to this, and may be, for example, a horizontally opposed type. Further, the invention is not limited to the one having two cylinder rows 11 and 21, but may be a W-type internal combustion engine having four cylinder rows, for example. Also in this case, exhaust passages are provided for each cylinder row, and are configured in such a manner that they are gathered together on the downstream side thereof, and an oxidation catalyst and a fuel addition valve are provided for each cylinder row. As long as the air-fuel ratio detection means is provided downstream of the collecting portion where the exhaust passages gather, the above embodiment can be used.

  In the above embodiment, the internal combustion engine having a plurality of cylinder rows is illustrated, but the internal combustion engine according to the present invention is not limited to this. In addition, for example, as shown in FIG. 5, the present invention can also be applied to an internal combustion engine 110 having only one cylinder row 111. In the exhaust passage 115 of the cylinder row 111, a first fuel addition valve 116A, a second fuel addition valve 116B, an oxidation catalyst 117, and an air-fuel ratio sensor 171 are provided in order from the upstream side. Further, a temperature sensor 153 for detecting the temperature increase ΔTC of the oxidation catalyst 117 is provided. Even in this case, when the abnormality diagnosis is executed for each fuel addition valve 116A (116B) through the electronic control unit 140 and the diagnosis for the predetermined fuel addition valve 116A (116B) is executed, the predetermined fuel addition valve 116A (116B) is executed. The fuel supply by the fuel addition valve 116B (116A) other than 116A (116B) may be prohibited. Here, when a command to supply fuel is output to the predetermined fuel addition valve 116A (116B), the change degree ΔA / F of the air-fuel ratio of the exhaust corresponding thereto corresponds to the supply of the fuel. It can be said that at least the predetermined fuel addition valve 116A (116B) is normal. Therefore, if there is an abnormal fuel addition valve 116A (116B), this can be specified.

  -In above-mentioned embodiment, although illustrated about the internal combustion engine provided with several fuel addition valve, the internal combustion engine which concerns on this invention is not restricted to this. In addition, for example, as shown in FIG. 6, only one fuel addition valve 216 may be provided in the exhaust passage 215.

  In the above embodiment, the internal combustion engine provided with only one oxidation catalyst between the fuel addition valve and the air-fuel ratio sensor in the exhaust passage is exemplified. However, as shown in FIG. Two oxidation catalysts 317A and 317B may be provided between the addition valve 316 and the air-fuel ratio sensor 371. In this case, temperature sensors 353A and 353B for detecting the temperature increase ΔTC of the oxidation catalysts 317A and 317B may be provided.

  In the above embodiment, when abnormality diagnosis is performed, a command for supplying fuel to the fuel addition valve is first output, and thereafter, a command for executing post injection is output to the fuel injection valve. Instead of this, it is also possible to first output a command to execute post-injection to the fuel injection valve, and then output a command to supply fuel to the fuel addition valve.

  In the above embodiment, the air-fuel ratio sensor is exemplified, but such an air-fuel ratio sensor is not an essential component in the control device for an internal combustion engine according to the present invention. That is, as shown in FIG. 8, the fuel addition valve 416 and the oxidation catalyst 417 are provided in the exhaust passage 415 of the internal combustion engine 410 in order from the upstream side. Further, a temperature sensor 453 for detecting the temperature increase ΔTC of the oxidation catalyst 417 is provided. However, the air-fuel ratio sensor (air-fuel ratio detection means) is omitted. Even in this case, a command to supply fuel is output to the fuel addition valve 416 through the electronic control unit 440, and the temperature increase ΔTC of the oxidation catalyst 417 accompanying this is not corresponding to the supply of the fuel. In this case, it can be said that at least one of the fuel addition valve 416 and the oxidation catalyst 417 is abnormal (cases 2, 3, and 4 in FIG. 2). In addition, when a command to execute post injection is output to the fuel injection valve 414 through the electronic control unit 440, and the temperature increase ΔTC of the oxidation catalyst 417 corresponding thereto corresponds to the supply of the fuel. It can be said that at least the oxidation catalyst 417 is normal (in FIG. 2, cases 1 and 3 correspond). Accordingly, a command to supply fuel is output to the fuel addition valve 416, and the accompanying temperature increase ΔTC of the oxidation catalyst 417 does not correspond to the fuel supply, and the fuel injection valve When a command to execute post-injection is output to 414, and the accompanying temperature increase ΔTC of the oxidation catalyst 417 corresponds to the supply of the fuel, the oxidation catalyst 417 is normal and the fuel It can be diagnosed that the addition valve 416 is abnormal (case 3 in FIG. 2).

  In short, a fuel injection valve that supplies unburned fuel to the oxidation catalyst by injecting fuel into the cylinder at a time that does not contribute to engine combustion, and an oxidation catalyst that accompanies fuel supply by the fuel addition valve or fuel injection valve. A temperature rise detecting means for detecting a temperature rise and a diagnostic means for diagnosing whether or not the oxidation catalyst and the fuel addition valve are abnormal, and outputs a command to supply fuel to the fuel addition valve at the time of the diagnosis, The temperature increase of the oxidation catalyst is not corresponding to the supply of the fuel, and a command to supply the fuel to the fuel injection valve is output, and the temperature increase of the oxidation catalyst is If it is a thing corresponding to supply of this, what is necessary is just to diagnose that an oxidation catalyst is normal and a fuel addition valve is abnormal.

  In the above embodiment, an example is provided that includes a fuel injection valve that supplies unburned fuel to the oxidation catalyst by injecting fuel into the cylinder at a time that does not contribute to engine combustion, that is, by performing post injection. However, such a fuel injection valve is not an essential component in the control apparatus for an internal combustion engine according to the present invention. That is, as shown in FIG. 9, a fuel addition valve 516, an oxidation catalyst 517, and an air-fuel ratio sensor 571 are provided in the exhaust passage 515 of the internal combustion engine 510 in order from the upstream side. Further, a temperature sensor 553 is provided for detecting the temperature increase ΔTC of the oxidation catalyst 517. However, the fuel injection valve for performing post injection is omitted. Even in this case, a command to supply fuel is output to the fuel addition valve 516 through the electronic control unit 540, and the temperature increase ΔTC of the oxidation catalyst 517 associated therewith does not correspond to the fuel supply. In this case, it can be said that at least one of the fuel addition valve 516 and the oxidation catalyst 517 is abnormal (cases 2, 3, and 4 in FIG. 2). Further, when the change degree ΔA / F of the air-fuel ratio of the exhaust gas in accordance with the command corresponds to the supply of the fuel, it can be said that at least the fuel addition valve 516 is normal (in FIG. 2). For these reasons, a command for supplying fuel to the fuel addition valve 516 is output, and the accompanying temperature increase ΔTC of the oxidation catalyst 517 does not correspond to the supply of the fuel. If the accompanying change in the air-fuel ratio ΔA / F of the exhaust corresponds to the supply of the fuel, it can be diagnosed that the oxidation catalyst 517 is abnormal and the fuel addition valve 516 is normal.

  In short, a temperature rise detection means for detecting the temperature rise of the oxidation catalyst accompanying the fuel supply by the fuel addition valve, an air fuel ratio detection means for detecting the air fuel ratio of the exhaust gas provided at the downstream side of the oxidation catalyst in the exhaust passage, A diagnostic means for diagnosing the presence or absence of an abnormality in the oxidation catalyst and the fuel addition valve, and at the time of the diagnosis, outputs a command to supply fuel to the fuel addition valve, and the temperature rise of the oxidation catalyst resulting from this is If the change in the air-fuel ratio of the exhaust gas corresponding to this does not correspond to the supply of the fuel, the oxidation catalyst is abnormal and the fuel addition valve is normal Anything that can be diagnosed.

  10, 110, 210, 310, 410, 510 ... internal combustion engine, 11 ... first cylinder row, 12, 22 ... combustion chamber, 13, 23 ... accumulator piping, 14, 24, 114, 214, 314, 414 ... fuel injection Valve 15, first exhaust pipe 16, 26, 116 A, 116 B, 216, 316, 416, 516, fuel addition valve, 17, 27, 117, 217, 317 A, 317 B, 417, 517, oxidation catalyst, 21,. 2nd cylinder row, 25 ... 2nd exhaust pipe, 30 ... 3rd exhaust pipe, 30A ... Collection part, 31 ... Filter, 40, 140, 240, 340, 440, 540 ... Electronic control unit, 51, 61 ... Upstream side Exhaust temperature sensor, 52, 62 ... downstream exhaust temperature sensor, 71, 171, 271, 371, 471, 571 ... air-fuel ratio sensor, 111, 211, 311, 411, 511 ... cylinder row, 11 , 215,315,415,515 ... exhaust passage, 153,253,353A, 353B, 453,553 ... temperature sensor.

Claims (8)

An oxidation catalyst provided in the exhaust passage;
An air-fuel ratio detecting means that is provided downstream of the oxidation catalyst in the exhaust passage and detects the air-fuel ratio of the exhaust;
A fuel addition valve that is provided upstream of the oxidation catalyst and the air-fuel ratio detection means in the exhaust passage and supplies fuel to the oxidation catalyst;
A fuel injection valve that supplies unburned fuel to the oxidation catalyst by injecting fuel into the cylinder at a time that does not contribute to engine combustion;
A temperature rise detection means for detecting a temperature rise of the oxidation catalyst accompanying the supply of fuel by the fuel addition valve or the fuel injection valve;
Diagnostic means for diagnosing the presence or absence of abnormality of the oxidation catalyst and the fuel addition valve,
The diagnostic means
At the time of the diagnosis, a command to supply fuel is output to the fuel addition valve, and the temperature rise of the oxidation catalyst accompanying this is not corresponding to the supply of the fuel, and to the fuel injection valve In contrast, when a command to supply fuel is output and the temperature increase of the oxidation catalyst corresponding to the command corresponds to the supply of the fuel, the oxidation catalyst is normal and the fuel addition valve is While diagnosing it as abnormal,
At the time of the diagnosis, a command to supply fuel is output to the fuel addition valve, and the temperature increase of the oxidation catalyst is not corresponding to the supply of the fuel, and the exhaust of the exhaust gas accompanying this is not. When the change rate of the fuel ratio corresponds to the supply of the fuel, the oxidation catalyst is abnormal and the fuel addition valve is diagnosed as normal,
The diagnosis is executed for each of the plurality of fuel addition valves provided, and when the diagnosis for the predetermined fuel addition valve is executed, fuel supply by a fuel addition valve other than the predetermined fuel addition valve is prohibited. In a control device for an internal combustion engine,
The internal combustion engine comprises a plurality of cylinder rows,
The exhaust passage is provided separately for each cylinder row, and is configured in such a manner that the exhaust passages gather together on the downstream side thereof,
The oxidation catalyst and the fuel addition valve are provided separately for each cylinder row,
The control apparatus for an internal combustion engine, wherein the air-fuel ratio detection means is provided downstream of a collecting portion where the exhaust passages gather. The control apparatus for an internal combustion engine according to claim 1 ,
The diagnostic means outputs a command to supply fuel to the fuel addition valve at the time of the diagnosis, and the change degree of the air-fuel ratio of the exhaust gas accompanying this is not corresponding to the supply of the fuel, In addition, a command to supply fuel to the fuel injection valve is output, and when the temperature rise of the oxidation catalyst is not corresponding to the fuel supply, the oxidation catalyst and the fuel addition valve A control apparatus for an internal combustion engine, characterized in that both are diagnosed as abnormal. The control apparatus for an internal combustion engine according to claim 2 ,
The diagnostic means outputs a command to supply fuel to the fuel addition valve at the time of the diagnosis, and when the change degree of the air-fuel ratio of the exhaust gas accompanying this does not correspond to the supply of the fuel, The output of the command to the fuel addition valve is stopped, while a command to supply fuel to the fuel injection valve is output, and the oxidation catalyst and the fuel addition are based on the temperature rise of the oxidation catalyst accordingly A control device for an internal combustion engine, characterized by diagnosing the presence or absence of a valve abnormality. The control apparatus for an internal combustion engine according to claim 3 ,
When the degree of change in the air-fuel ratio of the exhaust gas according to the output of the command to the fuel addition valve corresponds to the supply of the fuel, the diagnosis means detects abnormality of the oxidation catalyst and the fuel addition valve. A control device for an internal combustion engine, wherein output of the command to the fuel injection valve is prohibited in order to diagnose presence or absence. The control apparatus for an internal combustion engine according to any one of claims 1 to 4 ,
A control device for an internal combustion engine, wherein a filter for collecting particulate matter contained in the exhaust gas is provided downstream of the collecting portion in the exhaust passage. The control apparatus for an internal combustion engine according to claim 5 ,
The control unit for an internal combustion engine, wherein the diagnosis means executes the diagnosis only immediately after the start of the internal combustion engine. The control apparatus for an internal combustion engine according to claim 5 ,
An exhaust gas temperature detecting means for detecting the temperature of the exhaust gas flowing into the filter;
The control unit for an internal combustion engine, wherein the diagnosis unit executes the diagnosis only when the temperature of the exhaust gas detected by the exhaust gas temperature detection unit is equal to or higher than a predetermined temperature. In the control device for an internal combustion engine according to any one of claims 1 to 7 ,
The temperature rise detection means has a downstream exhaust temperature sensor that detects the temperature of the exhaust gas flowing out of the oxidation catalyst, and detects the temperature increase of the oxidation catalyst based on the detection result of the downstream exhaust temperature sensor. A control device for an internal combustion engine.

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